Automatic machine-gun.



W. H. VPRITCHETT. AUTOMATIC MACHINEY GUN. APPLICATION FILED DEc.22.VI9Is.

Patented Mar. 11,1919.

A 7 SHEETS-SHEET l.

I W m k Q I I .I N\ NK K MMMN MN NNI mur Nm.\| I /m\ N I .RIN QNI Q I N% )IIN \\m\ t I I@ Patented Mar. 1l,V 1919.

7 SHEETS-SHEET 2.

W. H. PRITCHETT.

AUTOMATIC MACHINE GUN. APPLICATION man DEc.2z. 1916 Patented Mar. 11,1919.

W. H. PIIITCHETI. AUTOMATIC MACHINE GUN. APPLICATION FILED DEC.22. I9I6.

Patented Mar. 11, 1919.

I SHEETS-SHEET 4.

Nk J QN NN N SN mm. NMX@ NMC- N mk N NN. @Nm n RN.

W. H. FHIIUHtTT.

AUTOMATIC MACHINE GUN.

APPLICATION FILED 050.22. IsIs.

Patented Mar'. 11,1919.

I SHEETS-SHEET 5.

I w N... wm C j I I.. I .I I A.. @Ml IWW. Q N

jme...

W. H. PRITCHETT.

AUTOMATIC MACHINE GUN. APPucATloN man 0m22.191s.

Patented Mar. 11, 1919.

7 SHEETS-SHEET 6.

W. H. PRITCHETT.

AuomAnc MACHINE GUN.

APPLICATION FILED DEC.22. |915. 1,297,240. Patented Mar. 11,1919.

1 SHEETS-SHEET 7- UNITED STATES PATENT OFFICE.

WILLIAM H. PRITCHETT, 0F CARTERSVILLE, GEORGIA.

AUTOMATIC MACHINE-GUI?.

Specification of Letters Patent.

Vreferenced Mar. 11, 1919.

Application med December 22, 1916. serial No. 138,52*'5.

My invention relates to improvements in v machine guns,.and is intended to provide a piece ,which may he fired either automatically or single shot, and either from the 'shoulder from a suitable rest, or from a4 -to clear the muzzle before the breech bolt has movedan appreciable distance to the rear.

The rearwardA movement of 'the' massive breech bolt lis not only taken care of by compressing the main, or return, spring, but is also arrested by a pneumatic' dash pot arrangement, mounted on the rear end-of the receiver, as will be hereinafter more fullyA described,

Incident to the return of the breech bolt to the rearward position, the empty cartridge case is'extracted 'and ejected.

. Certain means forcocking .the piece by hand and for locking same in the single shot or firing position are also provided.

My invention is especially intended to provide an automatic gun having very few'- parts, which is of simple and rugged construction, and which is not so apt to get out of order as are the machine guns with the multiplicity of partsY now generally in use.

These and the other details of the invention will be more fully understoood after y reference to the accompanyingdrawings, in

- which similar parts are indicated by similar reference symbols throughout the several views.

Figure 1 is a side elevation showing the complete piece as seen from the right;

Fig. 2 is a similar view showing the piece as seen from the left;

Fig. 3 is a view on a larger scale of the breech end of the piece shown in Fig. 2,

parts of the mechanism being shown in` dotted lines;

Fig. 3a shows the barrel end of the piecewith the inclosing casing, which, when joined to Fig. 3, would constitute the whole plece;

Fig. 4a shows the barrel end of tha'piece, the breech end of which is shown in Fig. 4, both being pl'an views; r

Fig. 5 is'a view of the barrel andvf Casin looking in the muzzle, as seen from the le of Fig. 3a;

Fig. 6 is a view of the barrel and casing, as seen from the right of Fig. 3, and looking towardthe front;

Fig. 7`shows a central section through the receiver made by the horizontal plane 7-7 of Fig. 3, parts .being shown in elevation,

ward or firing position;

Fig. Taf'shows a similar section through the barrel end of the piece, this section being taken along the line 73- a of Fig. 8iL and looking in the direction of the arrows;

Fig. 8 is a central vertical section through the receiver along the line 8--8 of Fig. 4,

parts being 'shown in elevation, and the breech bolt being shown in its rearmost position;

' and the breech bolt belng shown in the for- Fig. 8a shows a similar section through the L barrelend of the piece this section being taken on the line 8--8 o Fig. 7a; Fig. 9 shows a section along-the line `9--9 -gof-Fig. 8a, and looking in the direction of the arrows;

Fig. 10 showsa section along the linel 10-10 of Fig. 8a, and looking in the direction of the arrows;

' Fig. 11 is a detail view showing the breech bolt, with the extractorattached thereto, detached from the gun;

Fig. 12 shows a section alon the lineA 12-12 of Fig. 3,'1ooking in the direction of the arrows;

Fig. 13 is a detail showing the engagement of the trigger and Sear; Y

Fig. 14 shows a section through the feed Fig. 18 along the line 19-19, and looking in the direction of the arrows.

The piece comprises the following princi al parts:

he receiver A carried by the stock A',-

the barrel B secured to the receiver, having its xcasing C spaced away therefrom, the

breech bolt D with its cooking arm D', the main spri-n E, the firing 1n F, the extractor G, t e ejector H, the ocking lever I, the lever springI, the trigger J the Sear K, the pneumatic dash pot M, and the feed.

hopper P. rI hese, with any suitable form of ront and rear sights, constitute all of the essential elements ofthe piece.

' In Figs 1 and 2 I have shown a sling strlalp Q, provided. .l aving thus stated generally the several parts of the piece, I will now describe the same more in detail.

The receiver A is provided on the front j end with internal screw threadsV 1, adapted to engage the external screw threads 2 on the breech of the barrel; and the receiver is chambered to receive the breech bolt and main spring and parts carried thereby, and is provided with an annular shoulder 3 to engage the corresponding shoulder 4 on the breech bolt D when the latter is in the forward position as shown in Fig. 7. The receiver is also provided with the ide slot 5 for the cockin arm D', with t e ejector slot 6 and with 'e opposite slot 7, in which the ejector H is pivoted. The receiver is also provided with the feed opening 9 beneath the hopper P, see Fig. 8.

The barrel B is screwed to the forward end of the receiver and is provided with a plurality of radially disposed lu S211, to which the casing C is attached, as y means of the screws 12. This casing extends somewhat beyond themuzzle of the gun so that when the gun is fired, the powder gases will suck air through the air space between the arrel and the casing, and will thus cool the aI'Ie The frontvsight arm' 13 is connected to the barrel near its muzzle and projects out to one side thereof, as shownin' Fig. 4a, and the sight 14 projects beyondand to one side of the casing and in line with the rear sight 15, which is carried by the lug 16,-projecting from the side. of the barrel near the breech, as shown in Figs. 4 and 10.

The breech bolt D is perforated axially as at 20 (see Fig. 7) to receive the firmg pin F; and its body portion 21 is shouldered as at 22 to engage the main spring E. Thu

heel of the breech bolt 23 is reduced in diameter and terminates in thescrew cap 24, which screw cap is perforated as at 25 to permit the escape of air therethrough; and this cap serves to limit the rearward travel ofthe firing pin and also protect the bore 20 through the breech bolt from taking in any foreign matter which would be likely to impair the free movement of the firing 1n. p The forward end of the bodyportion 21 of the breech bolt is shouldered as at 4, as

already described, to engage the shoulder 3 in the receiver when the breech bolt reaches the' forward position'; and the forward end of the breech bolt carries 'the extractor G in the form of a leaf'spring having a claw 26 and the cam face 27. When the breech bolt is driven to the rear by the force of the powder gases, this cam face 27 strikes the cam arm 28 `of the ejector Hand causes the ejector to impart a quick blow to the cartridge case, throwing said case through the opening 6.

The head of the breech bolt should be of no greater vertical diameter, preferably of less diameter'than the rim of the cartridge case, for when the bolt moves to the rear both the boltand the empty cartridge case pass under the lower cartridge. The lower cartridge then drops into the receiver in front of the bolt. On again moving forward the bolt shoves the lower cartridge vinto its firing seat, the second cartridge (which now becomes the lower) riding on top of the bolt. Itis for this reason only that the vertical diameter of the forward or'tion ofl the. bolt can not be greater than t e diameter of the base of the cartridgecase, otherwise the bolt in i'tsforward motion would take against more than one cartridge. i

This obviates the necessity for any mechanical device for delivering the 4cartridges -seratim from the magazine hopper, which is one of the chief objections tothe feed mechanism `of all the automatic guns now in use. The serzatm feed mechanism is invariably complicated, requiring numerous small and delicate parts.

The cooking arm D', carried by the breech bolt, reciprocates in the guide groove 5.

The firing pin F is in the form of a long rod,mounted in and passing through the longitudinal axis of the breech bolt. It is provided with a notch 30 (see Figs. 7 and 8), adapted to engage the claw 31 of the firing pin latch 32 (see Fig. 8), which latch is pivoted as' at 33, and has an arm 34 normally pressed outward by the spring 35 so that when the firing pin is in the rearward position, having its rear end bringing up against the inner face of the screw cap 24,

- the claw 31 will engage in the notch 30, and

motion being will hold the firing pin against forward movement, as shown in Fig. 8.

This arm 34 travels in a guide groove 36- in the inner wall of the receiver, as shown in Fig. 8; and when the breech bolt is in the forward position, this arm 34 will engage the cam 4face 37 at the end of said groove 36,

and will trip the claw 31 out o f engagement with the notch 30, permitting the ring pin to fly forward of its own inertia, its forward arrested by the pin bringing up against t e primer of the cartridge case. In4 order to prevent the firing pin from beingthrown out of its seat in the breech bolt after the last cartridge has been ired, I

provide the tapered shoulders 2()a (see Figs. 7 and 8) at the forward end of the bore 20 in the breech bolt, which will arrest the forward movement of the firing pinv in the breech bolt after the point of the pin has projected forward the requisite distance for eX- ploding the primer.

The-piece is cocked bypulling the cocking arm D backward against the action of the spring E, which would cause the catch 40 of the locking lever I to engage said cooking .-arm, as shown in Fig. 15. This locking lever is pivoted as at 41 to the side of the receiver and has' an arm 42, which is pressed upward by the spring I against the stop 43.

As the breech bolt is moved to the rear either under the action of the cooking arm D or the pressure of the powder gases, this cooking arm D will wedgeu the cam face 44 of the cooking lever until t e cooking arm has reached the position shown in Fig. 15, when the spring I Awill cause the catch 40 to snap in front-of the cooking arm and will hold the breech bolt in the rearward position until said locking lever is tripped, which may be done by pressing down on the arm 'lug 51 into the engaging position.

shown in Fig. 16 when the catch 46 will engage the end of the lever arm 42 and will hold the catch 40 out of engagement with the cocking arm D', the parts then being in the position shown in LFig. 16. When the parts are in this position, the breech bolt can be reciprocated indenltely rearward under the pressure of the powder gases and forward under the pressure of the main spring.

The trigger and sear are shown in Figs. 8 and 13.

The Sear K is pivoted to the receiver at 50, and has a lug 51 projecting upwardly therefrom, which passesL through an opening 52 in the receiver and projects into the line of travel of the breech bolt except when thrown out of engagement by the trigger.

The sear terminatesA rearwardly in the sear spring 54, which normally throws the ivoted as at The trigger J is 60 to lugs on the receiver, and -1s provided with an arm- 61 adapted to press up on the-scar spring 54, and to pull the lug 51 clear of the breech bolt. Thus the parts being in the position shown in Fig. V8, if the trigger be pulled backward, the breech bolt willvbe released and will fly forward under the action of the spring E; and it will be free to reciprocate backward and forward as long as the pull on the trigger is continued.

Thus', the gun will continue firing automatically as long as the trigger is pulled and the ammunition supply is maintained. The trigger and sear are shown in the position for automatic firing in Fig. 16.

To control the rearward movement of the breech bolt under the pressure of the powder gases, I provide not only the usual return spring E; but also a pneumatic dash pot arrangement M, shown in Figs. 3, 4, 7, 8, and in detail in Figs. 17 to 19. This comprises a hollow block secured to the receiver in When the breech bolt is thrown back violently, as by the pressure "of the powder gases, after the gun has been fired, the air in the receiver in vrear ofthe breech bolt will be forced backward, and willl be compressed, and a part of it will be trappedin the chamber 72 and this air will be highly compressed and will serve as a dash pot not only to check the backward movement of the breech bolt, but its elasticity will also assist the mam spring E in the initial forward movement of the vbreech bolt, .thus relieving the shock of the reverse movement of the breech bolt from the rearward to the forward direction.'

- In case the pneumatic pressure should become too great, I provide a relief valve 78, controlling the escape passage 79 (see Figs. 7 and'19). This relief valve may be set at the desired position and clamped thereat by means of the set screw 80 (see Flgs. 17 and 18) engaging ythe head 78a of the relief valve 78.

By adjusting the opening in the escape passage 79, the maximum pneumatic pressure in the chamber 72 may be regulated asi desired.

After the heel of the breech bolt leaves the chamber 72, and the breech bolt continues to fly forward, there will be apar-v tial vacuum created in the rear end of the receiver and the check valve 74 will be moved off its seat against the action of the spring 76, and air will rush in to supply the loss of air that has escaped through the relief passage 79.

The ammunition may be supplied to the piece in any convenient way; but I prefer to'use a feed hopper of the shape shown in Figs. 3, 4, 8 and 14, in which the sides 81 and 82 of the hopper taper downward to a narrow throat 83 and in which the two sides are provided with staggered inclinedl surfaces 84, 85, 86, 87, 88 and 89, which tend to cause the cartridges to lfeed downward toward the throat 83 without becoming jammed in the hopper. The cartridges are fed downward by their own weight.

To prevent cartridges' in the hopper from feeding tclthe gun except when desired, I provide a ut-off gate or blade 90 project-A ingjinto the throat of the hopper, as shown in Fig. 14. This gate is secured to a leaf spring 91, pivoted as at 91' to the side of the hopper, and projecting somewhat -beyond the edge of the hopper, as shown at 93, in Figs l, 2, and 8. By bringing this gate out of its slot and letting it rest against the outside of the hopper, the cartridges will fall down quickly by gravity.; but by bringing the gate back into the slot and allowing it to project into the hopper, it will stop the further downward feed of the cartridges.

Thus when it is desired to suspend firing temporarily the gate 90 is thrown to the closed position.- The cartrid es beneath same `vwill'bedired 'automaticaIly and the empty shells ejected, leaving the bottom cartridge in the hopper resting on .said gate and at a distance from the breech bolt .when it returns ,to the closed position.

Since .the headv ofthe breech bolt is apt to be highly heated incident to the previous rapld firing of the piece, the .fact that the lower cartridge in the hopper is entirely clear of contact with the hot vbre/ech bolt will prevent any danger from premature explosion of saidv cartridge, due to the proximity of the heated headof the .breech bolt.

In various automatic guns now in use,

when firing is arrested, before the feed supply is exhausted,l the last cartridge rests on the head of the breech bolt, and there is more or less danger from premature explolmeans may be provided for locking it in the vertical position, when desired, such as the removable pin 101.

The hopper may be provided with a suitable cover 94 pivoted to one side thereof as at 95, and secured to the other side thereof by the spring catch 96.

When the hopper is swung backward and rests on the top-of the receiver the cover 94 and gate90 will prevent the cartridges from falling out of the hopper.

The operationof the device is as follows: Suppose the hopper to be supplied with cartridges, and it is desired to fire single shots, see that the gate 90 is swung clear of the throat of the hopper and that the latch 45 is in the disengaged position shown in Fig. 15, and coc the piece by hand, then pull back on the trigger releasing the sear, andthe breech bolt will fly forward under the action of the main spring E, the lower cartridge in the feed chamber ywill be pressed forward into the cartridge fof the cartridge case. As soon as the breech bolt reaches the' closed position, the firing pinl latch will be automatically released and the firing pin will -fly forward under its own inertia, striking the primer and firing the cartridge.

As the projectile flies forward through the bore, the pressure of the powder gases will be exerted on the far greater mass of the breech bolt and theparts carried thereby, and the breech bolt will begin to move rearward about the time the projectile leaves the bore. The extractor will draw the empty cartridge case rearward until its cam face 27 strikes the shoulder arm 28 of the ejector I-I, when the ejector will flip the empty 'cartridge case out through the opening 6y in the side of the receiver. The breech bolt in its `rearward movement, carries with it the breech bolt will be started forward again by the initial impulse of the pressure by the compressed-air and the pressure of the spring E, and will continue its forward movement until the cooking arm D engages rear, press down on the lever arm 42 and -allow the cooking arm to move slightly for'- `Ward. This allows the catch 40 to ride on top of the cooking arm and at the saine time the sear arm 51 will take in its notch in the breech bolt at the shoulder 4.' The arm 51 alone is now holding the breech bolt to the rear. Now pull the trigger andthe gun will re a single shot, the breech bolt, on recoil, being again locked in its rear position by the latch 40. This cycle of operations may be repeated indefinitely.

For automatic firing, suppose the parts be at rest and the hopper provided with cartridges, set the locking lever in the posi.- tionshown in Fig. 16, and cock the piece by hand, by pulling backward on the cooking arm D', the sear will then be in the position shown in full lines in Fig. 8 and in dotted lines in Fig. 15; now pull on the trigger and release the scar, as shown in-F ig. 16;

and as longas the trigger is pulled back! ward and the hopper supplied with cartridges, the automatic firing will continue.

The relief valve 78 should be so adjusted that the pneumatic pressure in the dash pot chamber will bring the breech bolt to a stop just before the rear end of the breech bolt brings up against Ithe check valve 74.

The facility of the opening of the check valve 74 of the pneumatic dash pot may be increased or decreased by easing up or screwing down onv the lock nut 77,'on the valve stem 75, thus varying the tension' of the spring 76.

Special advantages claimed for this piece are:

I. Simplicity of construction, there being no delicate or complicated mechanism to break or get out of adjustment, thus practically eliminating jams, the chief diiiiculty Y with machine guns now in use.

II. The small number of moving parts, the principal vmoving parts being the breech bolt, the firing pin, thefiring pin locking lever, the main spring, andthe ejector.'

III. The breech bolt moves longitudinally in a straight line and does not have any turning-motion for locking,'therefore, it is possible to secure greater -rapidity of automatic fire. l

IV. The automatlc `ire may be continue-'1,'

it being unnecessary to cease ring to iill up the magazine hopper.

V. The gun can be easily operated by'one VIII. By having spare barrels with their cases, sights, etc., the barrel can be quickly changed in case it becomes overheated; but the gun .may be fired a large number of 'rounds without the barrel being overheated,

owing to the air cooling arrangement. shown.

IX. There is very slight recoil and very little shockat the end of the rearward stroke of the heavy breech bolt, thus contributing greatly to the accuracy of aim and direction of fire.

X. The ballistic qualities of the gun are l of very high order.

XI. The trigger and sear arrangement, forming a part of 'the firing mechanism, are extremely simple and the firing pin needs no spring to drive it forward, and no separate means for restoring the iiring pin to the proper position is needed.

It will be obvious that various modifications in the herein described construction and combination and arrangement of parts might be madewithout departing from the spirit of my invention. A

Having thus described my invention, what I claim and desire to secure by Letters Patent ofthe United Stat is:

1. In an automatic gun, the combination with a receiver, of a reciprocating breech bolt comprising a singlel piece slida'bly mounted'therein adapted to be forced rearward by the powder gases, aV main spring mounted in said receiver directly in rear of said breech bolt for returning said breech bolt to the closed position, a firing pin slidably mounted in said breech bolt, means for locking ysaid firing pin to said breech bolt during the reciprocating movement of said bolt, and means for automaticallv releasing said firing pin and allowing it to liy forward under its own inertia when the breech bolt reaches the closed position, substantially as.

-lockingsaid ring pin to s'aid breech bolt during the reciprocating movement of said 4bolt slidably mounted therein-adapted to be forced rearward by the powder gases, a main spring mounted in said receiver for returning said breech bolt to the closed position, a firing pin slidably mounted in said breech bolt, means for locking said firing pin to said breech bolt vduring the reciprocating movement of said bolt, and for automatically releasing said firing pin and allow-ing it to fly forward under its own inertia when the breech bolt reaches the closed position,

vcomprising a spring impressed latch carried by said breech bolt and having a'catch 4adapted to engage said firing pin, and an larm"'adapted to be 'tripped by said receiver as the breech bolt nears the forward limit of its travel, substantially as described.

4. In anl automatic gun, the combination with a receiver, of a reciprocating breech bolt slidably mounted therein adapted to be forced rearward by the powder gases,a main spring mountedl in said receiver for returning said breech bolt to the closed position, aring'pin slidably mounted in said breech bolt, means for locking said firing pin to said breech bolt during the reciprocating movement of said bolt, and for automatically releasing said ring pin and allowing it to fly forward 'under its own inertia when the breech bolt reaches the closed position, comprising a spring impressed latch carried by said breech bolt and having a catch adapted to engage said firing pin, and an arm Vadapted to-be tripped by said receiver as the breech bolt nears the forward limit of its travel, with a pneumatic dashf pot mounted at the end of' the receiver and adapted to arrest the rearward movement of said breech bolt, substantially as described.

5. In an automatic gun, the combination 'with a receiver, of a reciprocating breech bolt slidably -mounted therein adapted to be forced rearward by the powder gases, a main spring'mounted in said recelver for returning said breech bolt to the closed position, a -ring pin slidably mounted in said breech bolt, means' for locking said iring pin to said' breech bolt during the reciprocating mpvement of said bo t, means for automatically releasing said firing pin and allowing it to 'iiy forward under itsy own inertia when the breech bolt reaches 'the closed position, an extractor carried by said breech bolt, and provided with. a, cam face, and an ejector pivoted in said receiver, and having a short arm adapted to be struck by'said cam fac-e, substantially as described.

6. In an automatic gun, the combination with a receiver, of a reciprocating breech bolt slid-ably mounted therein adapted to be forced rearward by the powder gases, a main spring mounted in said receiver for returning said breech bolt to the closed position, a firing pin slidably mounted in said breech bolt, means for locking said firing pin to said breech bolt during the reciproeating movement of said bolt, means for automatically releasing said iring pin and allowingit to iy forward under its own inertia when the breech bolt reaches the closed position, an extractor carried by said breech bolt, and provided with a cam face, and an ejector pivoted in said receiver, and

having a short arm adapted to be struck by said cam face, with a pneumatic dash pot. mounted at the end of the' receiver and adapted to arrest the rearward movement of said breech bolt, substantially as iescrbed.

7. In an automatic gun, the combination witha receiver, of a reciprocating breech bolt slidably mounted therein adapted to be forced rearward by the powder ases, a main spring mounted in said recelvcr for returning said breech bolt 'tothe 'closed position, a firing pin slidably mounted in said breech bolt, means for locking said firing pin to said breech bolt during the reciprocatingmovement of said bolt, means for automatically releasing said firing pin and allowing it to fly-forward under its own ir'.- ertia when the breech bolt reaches the closed position, a sear pivoted to the receiver, and having an arm projecting into 'thepath of the vlbreech bol-t, and a spring arm, and a trigger piece having an arm adapted to engage -said spring arm of the scar, and to release said sear from-engagement with said bolt, substantially as descrlbed.

8. In an automatic gun, the vcombination with a receiver, of a reciprocating breech bolt slidably mounted therein adapted to be iiorced rearward by the powder ases, a main springm-ounted in said ,receiver for returnin lsaidsbreech bolt to the closed position, a ing -pin slidably mounted in said breech bolt, means for locking said pin to said breech bolt during the reciprocating movement of said bolt, means for automatically releasing said iiring pin and allowing it to fly forward under its own inertia when the breech boltv reaches the closed position, 'a sear p-ivoted te the receiver, and having an arm 4projecting into the path of the breech bolt, anda spring arm, anda trigger piecev having` an arm adapted -to en age said spri4 arm of the Sear, and to ease said scar m engage- -forced rearward by the powder gases, a

main spring mounted in said receiver for returning said breech bolt to the closed position, and a pneumatic dash pot mounted at the end arrest the rearward movement of said breech bolt, said dash pot comprising a hollow Vblock secured to the rear end of the receiver and having a chamber adapted to fit 'the heel of Ithe breech block, and a spring impr check valve normally closing said chamber against the escape of .air therefrom, but permitting the influx ofair as the breech bolt flies ,forward from its rearmost posi-tion, substantially as described.

10. In an lautomatic gun, the combination with .a receiver, of a reciprocating breech bolt slifdlably mounted therein adapted to be forced rearward by the powder gases, a main spring mounted in said receiver for returning said breech bolt to the closed position, and a pneumatic ldash pot mounted at the end of the receiver and adapted to arrest the rearward movement of said breech bolt, said dash 4pot comprising a hollow block secured to the rear end of the receiver and having a chamber adapted to fit the heel of the breech block, .and a spring impressed check valve normally closing said chamber against the escape of air therefrom, but permitting the inux of air as the breech bolt flies forward from its rearmost position, the said chamber being also provided with a relief passage, and a relief "alve controlling the opening through said relief passage,

substantially as described.

11. In an automatic gun, the combination with -a receiver, of areciprocatingbreech bolt slidably mounted therein adapted to be forced rearwardby the powder gases, a main spring mounted in said receiver for returning said breech bol-t to the closed position, la firing pin sli-dably mounted in said breech bolt, means for locking said firing pin to said breech bolt during the reciprocating mogement of said bolt, means for automatica ly releasing said firing 'pin and allowing it to fly forward under its own inertia when the breech bolt reaches the closed position, and a pneumatic dash pot mounted at the end of the receiver 'and adapted tot arrest the rearward movement of said'breech bolt, said dash pot comprising a hollow block secured to the rear end of the receiver and having a chamber adapted" to fit the heel of the' breech block, and a spring impressed check valve normally closing said chamber against of the receiver and adapted to the escape of air therefrom, but permitting the influx of air as the breech bolt flies forward from itsl rearmost position, -substantially as described. A

12. In an automatic gun, the combination with a receiver, of a reciprocating breech bolt slidably mounted therein adapted to be forced rearward by the 'powder gases, a main spring mounted in said receiver for returning said breech boltl to the closed position, a tiring pin slidably mounted in said breech b'olt, means for locking Vsaid firing pin to said breech bolt during the reciproeating movement of said bolt, means for automatically releasing said firing pin and allowing it to fly forward under its own inertia when the breech bolt reaches the closed position, and aA pneumatic dash pot' mounted at the end of the receiver and adapted to arrest the rearward movement of said breechA bolt, said dash pot compris# ing -a hollow block secured to the rear end of the receiver and having `a chamber adapted to fit the heel of the breech block, and a spring impressed check valve normally closing said chamber against the escape of air therefrom, but permitting the infiux of air as the breech bolt flies forward from its rearmost position, the said chamber being also provided with a relief passage, and a relief valve contro-lling the opening through said relief passage, substantially described.

13. In an automatic gun, the combination with a receiver, of a-reciprocating breech bolt slidably mounted therein adapted to be forced rearward by the powder gases, a main spring mounted in said receiver for 4returning said breech bolt to the closed po- 105 sition, a firing pin slidably mounted in sai breech bolt, a spring impressed latch for locking said firing pin to said breech bolt during the reciprocating movement of said bolt, and an arm on said latch adapted to engage a cam face on the receiver for autbmatically releasing said firing pin and allowing it to iy forward under its own inertia when the breech bolt reaches the closed position, substantially as described.

14. In an automatic gun, the combination with a receiver, of a reciprocating breech bolt slidably mounted therein adapted to be' forced. rearward by the powder gases, a main spring mounted in said receivenfor returning said breech bolt to the closed position, a firing pin slidably mounted insaid breech bolt, a spring impressed latch for locking said firing pm to said breech bolt during the reciprocating movement of said bolt, and an arm on said latch adapted to engage a cam face on the receiver for automatically releasing said firing pin and allowing it to fly forward under its own inertia when the breech bolt reaches the closed position, with a pneumatic dash pot mount- `face, with a the end of t e receiver and adapted yto ar rest the rearward movement of said breech breech bolt, and provided with a cam face,

and an ejector pivoted in said receiver, and having short arm adapted to be struck by said ca face, substantially, as described.

16. In an automatic gun, the combination with a receiver, of a reciprocating breech boltslidably mounted therein adapted to be 4forced rearward by the powder returning said breech bolt to the closed position, an extractor carried by, said breech bolt, and provided withA a c m face, and an ejector pivoted in said. receiver, an having a short arm adapted to be struck by neumatic dash pot mou ted at bolt, substantially as described'.

17. Inan automatic gun, the combination f with a receiver, ofA a reciprocating breech bolt slldably-mounted therein adapted to b e forced rearward by the powder gases,-a main spring mounted in said receiver for returngases, a main sprlng mounted in said recelver for id cam Aaussagen) ing said breech bolt to the closed position, a

project into the path'of said cocking arm and to4 arrest the forward'movement of the breech bolt at a predetermined portion of its forward travel, with a pneumatic dash pot mounted. at the. end of the receiver and adapted to arrest the rearward movement of saidbreech bolt, substantially as described.

18. In an automatic gun, the combination with a receiver, of a reciprocating breech bolt slidably mounted therein adapted to be forced rearward by the powder gases, a main spring mounted in said receiver for returning said breech bolt to the closed position, a cocking arm carried by. said breech bolt, and a` sprmg impressed locking lever.

pivoted on said receiver and having a catch adapted to project into the path of said cocking arm and to arrest the forward movement of the breech bolt at a predetermined portion of its forward travel, with a latch4 mounted on the receiver, and 'adapted to hold saidlocking lever out of engagement with said cocking arm, when desired, with a pneumatic dash pot mounted at the .end of the receiver and adaptedto arrest the 'rearward movement of said breech bolt, substantially as described.

In testimony whereof I- aflix my signature.

WILLIAM H. PRITCHETT. 

